U.S. patent number 7,094,139 [Application Number 10/659,047] was granted by the patent office on 2006-08-22 for retaining ring with flange for chemical mechanical polishing.
This patent grant is currently assigned to Applied Materials, Inc.. Invention is credited to Dan A. Marohl, Ming-Kuei Tseng.
United States Patent |
7,094,139 |
Marohl , et al. |
August 22, 2006 |
Retaining ring with flange for chemical mechanical polishing
Abstract
A retaining ring has a generally annular body with a top
surface, a bottom surface, an inner diameter surface, and an outer
diameter surface. The outer diameter surface includes an outwardly
projecting flange having a lower surface, and the bottom surface
includes a plurality of channels.
Inventors: |
Marohl; Dan A. (San Jose,
CA), Tseng; Ming-Kuei (San Jose, CA) |
Assignee: |
Applied Materials, Inc. (Santa
Clara, CA)
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Family
ID: |
29712324 |
Appl.
No.: |
10/659,047 |
Filed: |
September 8, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20040152403 A1 |
Aug 5, 2004 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60445352 |
Feb 5, 2003 |
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Current U.S.
Class: |
451/442;
257/E21.23; 451/288; 451/398 |
Current CPC
Class: |
B24B
37/32 (20130101); H01L 21/30625 (20130101) |
Current International
Class: |
B24B
21/18 (20060101) |
Field of
Search: |
;451/36,41,59,63,285,286,287,288,289,290,397,398,442 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 747 167 |
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Dec 1996 |
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EP |
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0 776 730 |
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Jun 1997 |
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EP |
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0 790 100 |
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Aug 1997 |
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EP |
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0 841 123 |
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May 1998 |
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EP |
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0 988 931 |
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Mar 2000 |
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EP |
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1038636 |
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Sep 2000 |
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EP |
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2 307 342 |
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May 1997 |
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GB |
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2 336 121 |
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Oct 1999 |
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GB |
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12-225556 |
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Aug 2000 |
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JP |
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195222 |
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Feb 1999 |
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KR |
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2000-18619 |
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Apr 2000 |
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KR |
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2002-84818 |
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Nov 2002 |
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KR |
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Other References
"High-Tech Resins Boost Chip Production", Machine Design, Nov. 7,
1996, pp. 52+. ["Machine Design"]. cited by other .
"Advanced Engineering Plastics for Semiconductor Industry", DSM
Engineering (Polymer Corporation), 1996. ["DSM"]. cited by other
.
"Advanced Engineering Plastics for the Semiconductor Industry", DSM
Engineering (Polymer Corporation), 1997. ["DSM"]. cited by
other.
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Primary Examiner: Eley; Timothy V.
Attorney, Agent or Firm: Fish & Richardson P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
No. 60/445,352, filed on Feb. 5, 2003, which is incorporated by
reference herein.
Claims
What is claimed is:
1. A retaining ring comprising: a generally annular body having a
top surface, a bottom surface, an inner diameter surface, and an
outer diameter surface, wherein the bottom surface is configured to
contact a polishing pad during polishing and the outer diameter
surface includes a vertical surface, a tapered section and an
outwardly projecting flange having a lower surface parallel to the
top surface of the annular body, the vertical surface is adjacent
to the bottom surface and the tapered section extends upwardly and
outwardly from the vertical surface to the lower surface of the
flange.
2. The retaining ring of claim 1, wherein the tapered section forms
an angle of about 60.degree. relative to a plane parallel to the
bottom surface.
3. The retaining ring of claim 1, wherein the inner diameter
surface includes a tapered section having a circumference that is
greater toward the top surface than toward the bottom surface.
4. The retaining ring of claim 3, wherein the inner diameter
surface includes a vertical section between the tapered section and
the bottom surface.
5. The retaining ring of claim 3, wherein the tapered section of
the inner diameter surface forms an angle of about 80.degree.
relative to the top surface.
6. The retaining ring of claim 1, wherein the bottom surface
includes a plurality of channels.
7. The retaining ring of claim 1, wherein the top surface includes
a plurality of holes formed therein.
8. The retaining ring of claim 7, wherein the top surface includes
eighteen holes.
9. The retaining ring of claim 1, further comprising at least one
drain hale extending from the inner diameter surface to the outer
diameter surface.
10. The retaining ring of claim 1, wherein the inner diameter
surface has a radius of about 300 mm adjacent the bottom
surface.
11. The retaining ring of claim 1, wherein the greatest
circumference of the retaining ring is at the flange.
Description
BACKGROUND
The present invention relates generally to chemical mechanical
polishing of substrates, and more particularly to a retaining ring
for use in chemical mechanical polishing.
An integrated circuit is typically formed on a substrate by the
sequential deposition of conductive, semiconductive or insulative
layers on a silicon substrate. One fabrication step involves
depositing a filler layer over a non-planar surface, and
planarizing the filler layer until the non-planar surface is
exposed. For example, a conductive filler layer can be deposited on
a patterned insulative layer to fill the trenches or holes in the
insulative layer. The filler layer is then polished until the
raised pattern of the insulative layer is exposed. After
planarization, the portions of the conductive layer remaining
between the raised pattern of the insulative layer form vias, plugs
and lines that provide conductive paths between thin film circuits
on the substrate. In addition, planarization is needed to planarize
the substrate surface for photolithography.
Chemical mechanical polishing (CMP) is one accepted method of
planarization. This planarization method typically requires that
the substrate be mounted on a carrier or polishing head of a CMP
apparatus. The exposed surface of the substrate is placed against a
rotating polishing disk pad or belt pad. The polishing pad can be
either a "standard" pad or a fixed-abrasive pad. A standard pad has
a durable roughened surface, whereas a fixed-abrasive pad has
abrasive particles held in a containment media. The carrier head
provides a controllable load on the substrate to push it against
the polishing pad. A polishing slurry, including at least one
chemically-reactive agent, and abrasive particles if a standard pad
is used, is supplied to the surface of the polishing pad.
SUMMARY
In one aspect, the invention is directed to a retaining ring that
is a generally annular body having a top surface, a bottom surface,
an inner diameter surface, and an outer diameter surface. The outer
diameter surface includes an outwardly projecting flange having a
lower surface, and the bottom surface includes a plurality of
channels.
Implementations of the invention may include one or more of the
following features. The lower surface may be substantially parallel
to the top surface and the bottom surface. The outer diameter
surface may include a tapered section having a circumference that
is greater toward the bottom surface than the top surface. The
outer diameter surface may include a vertical section between the
tapered section and the bottom surface. This tapered section may
form an angle of about 60.degree. relative to the bottom surface.
The inner diameter surface may include a tapered section having a
circumference that is greater toward the top surface than the
bottom surface. The inner diameter surface may include a vertical
section between the tapered section and the bottom surface. This
tapered section forms an angle of about 80.degree. relative to the
top surface. The bottom surface may include channels. The top
surface may include a plurality of holes, e.g., eighteen holes,
formed therein. At least one drain hole may extend from the inner
diameter surface to the outer diameter surface. The inner diameter
surface may have a radius of about 300 mm adjacent the bottom
surface.
In another aspect, the invention is directed to a retaining ring
for a carrier head for use in chemical mechanical polishing having
a mounting surface for a substrate. The retaining ring has a
generally annular lower portion having a bottom surface for
contacting a polishing pad, wherein the bottom surface includes a
plurality of channels, and a generally annular upper portion
secured to the lower portion, the upper portion having an outer
diameter with an annular projection.
Implementations of the invention may include one or more of the
following features. The annual projection may have a horizontal
lower surface, a horizontal upper surface and a vertical
cylindrical outer surface connecting the lower surface and the
upper surface. The lower portion may have an inner diameter surface
with a radius of about 300 millimeters. The outer diameter surface
may include a tapered section wherein a circumference of the
tapered section is greater toward the upper portion than the lower
portion. The lower portion and the upper portion can be formed as a
single unit.
In another aspect, the invention is directed to a retaining ring
for use in chemical mechanical polishing having a mounting surface
for a substrate. The retaining ring has an inner diameter surface
with a tapered surface. A circumference of the inner diameter of
the retaining ring is smaller toward a bottom surface than a top
surface of the retaining ring.
Implementations of the invention may include one or more of the
following features. The inner diameter surface may include a
cylindrical vertical surface.
One potential advantage of the invention is that, as the carrier
head is lowered to receive the substrate at the transfer station,
the tapered wall of the outer diameter of the retaining ring can
engage the inner surface of the load cup to guide the retaining
ring into alignment with the substrate. This improves concentricity
of the retaining ring and the substrate held by the transfer
station and improves reliability of the loading process.
Another potential advantage of the invention is that the flat lower
surface of the flange on the outer diameter of the retaining ring
can engage and rest on the upper surface of the load cup. This
improves parallelism between the carrier head and the substrate and
improves reliability of the loading process. In addition, the flat
lower surface of the flange will properly engage the upper surface
of the load cup to ensure parallelism even if the bottom surface of
the retaining ring has been worn.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view, partially cross-sectional, of a
retaining ring according to the present invention.
FIG. 2A is a bottom view of the retaining ring of FIG. 1.
FIG. 2B is a side view of the retaining ring of FIG. 1.
FIG. 3 is a perspective view of the retaining ring of FIG. 1.
FIG. 4 is a cross-sectional view of the retaining ring along line
4--4 in FIG. 3.
DETAILED DESCRIPTION
Referring to FIGS. 1, 3 and 4, a retaining ring 100 is a generally
annular ring that can be secured to a carrier head of a CMP
apparatus. A suitable CMP apparatus is described in U.S. Pat. No.
5,738,574 and a suitable carrier head is described in U.S. Pat. No.
6,251,215, the entire disclosures of which are incorporated herein
by reference. The retaining ring 100 fits into a loadcup for
positioning, centering, and holding the substrate at a transfer
station of the CMP apparatus. A suitable loadcup is described in
U.S. Pat. No. 6,716,086, entitled EDGE CONTACT LOAD CUP (EP
Publication No. 1061558), and assigned to the assignee of the
present invention, the entire disclosure of which is hereby
incorporated.
The retaining ring 100 can be constructed from two pieces. The
first piece, the lower portion 105, has a flat bottom surface 110
which includes eighteen channels 210 or grooves, shown in FIGS. 2A
and 2B (there could be a different number of channels). The
straight channels 210 begin at the inner circumference and end at
the outer circumference of the bottom surface 110 and can be
distributed at equal angular intervals around the retaining ring
100. The channels are typically oriented at 45.degree. relative to
a radial segment extending through the center of the retaining ring
100, but other angles of orientation, such as between 30.degree.
and 60.degree., are possible.
Referring again to FIGS. 1, 3 and 4, an inner diameter 115 of the
lower portion 105 forms a straight vertical cylindrical surface. In
contrast, the outer diameter surface 120 of the lower portion 105
includes both a vertical portion 125, starting adjacent the bottom
surface 110, and an outwardly sloping portion 130 which extends
upwardly from the vertical portion 125. The outwardly sloping
portion 130 of the outer diameter may form an angle of about
60.degree. relative to the bottom surface 110 of the retaining
ring. A flat top surface 135 of the lower portion 105 is parallel
with the bottom surface 110. This top surface 135 meets the sloped
portion 130 of the outer diameter surface 120 at an obtuse angle
and meets the inner diameter 115 at a substantially right angle.
The inner diameter 115 defines a substrate receiving recess 140 of
the retaining ring 100.
The lower portion 105 of the retaining ring 100 can be formed from
a material that is chemically inert to the CMP process. The
material should be sufficiently elastic that contact of the
substrate edge against the retaining ring 100 does not cause the
substrate to chip or crack. However, the retaining ring 100 should
not be so elastic as to extrude into the substrate receiving recess
140 when the carrier head puts downward pressure on the retaining
ring 100. The retaining ring 100 should also be durable and have a
low wear rate, although it is acceptable for the retaining ring 100
to wear away. For example, the retaining ring 100 can be made of a
plastic, such as polyphenylene sulfide (PPS), polyethylene
terephthalate (PET), polyetheretherketone (PEEK), polybutylene
terephthalate (PBT), polytetrafluoroethylene (PTFE),
polybenzimidazole (PBI), polyetherimide (PEI), or a composite
material.
The second piece of the retaining ring 100, the upper portion 145,
has a flat bottom surface 150 and a top surface 160 that is
parallel to the bottom surface 150. The top surface 160 includes
eighteen holes 165 to receive bolts, screws, or other hardware for
securing the retaining ring 100 and carrier head together (there
could be a different number of holes). Additionally, one or more
alignment apertures 170 can be located in the upper portion 145. If
the retaining ring 100 has an alignment aperture 170, the carrier
head can have a corresponding pin that mates with the alignment
aperture 170 when the carrier head and retaining ring 100 are
properly aligned.
The outer diameter surface 175 of the upper portion 145 includes an
outwardly sloped section 190, a horizontal section 185, and a
vertical section 180. The outwardly sloping section 190 of the
outer diameter surface 175 may form an angle of about 60.degree.
relative to the bottom surface 110 of the retaining ring. The inner
diameter surface 155 of the upper portion 145 is sloped outwardly
so that the top of the inner surface diameter 155 has a greater
diameter than the bottom. The outwardly sloping inner diameter
surface 155 may form an angle of about 80.degree. relative to the
top surface 160 of the retaining ring. The top surface 160 meets
the outer diameter surface 175 at a substantially right angle,
whereas the bottom surface 150 meets the outer diameter surface 175
at an obtuse angle. The horizontal section 185 is parallel to the
top and bottom surfaces 160 and 150, respectively. The top surface
160, vertical section 180, and horizontal section 185 of the upper
portion 145 together form a flange 195.
The upper portion 145 of the retaining ring 100 can include one or
more drain holes 200, e.g., four drain holes spaced at equal
angular intervals around the retaining ring. These drain holes 200
extend through the retaining ring from the inner diameter surface
155 to the outer diameter surface 175, e.g., in the sloped section
190. The drain holes 200 can be tilted, e.g., higher at the inner
diameter surface than at the outer diameter surface. Alternatively,
the drain holes 200 can be substantially horizontal, or the
retaining ring can be manufactured without drain holes.
The upper portion 145 can be formed from a rigid material, such as
metal. Suitable metals for forming the upper portion include
stainless steel, molybdenum, or aluminum. Alternatively, a ceramic
can be used.
The lower portion 105 and the upper portion 145 are connected at
their top 135 and bottom 150 surfaces, respectively, to form the
retaining ring 100. When the upper portion 145 and lower portion
105 are aligned and mated, the retaining ring 100 has a unitary
tapered surface 130, 190 at a constant angle along the outer
diameter surface 120, 175. The two parts can be joined using an
adhesive, screws, or a press-fit configuration. The adhesive layer
can be a two-part slow-curing epoxy, such as Magnobond-6375.TM.,
available from Magnolia Plastics of Chamblee, Ga.
When the retaining ring 100 is secured to a base of a carrier head,
the circumference of the top of the outer diameter 180 can be
substantially the same as the circumference of the base of the
carrier head so that no gap exists along the outer edge of the
carrier head.
In normal operation of the CMP apparatus, a robotic arm moves a 300
mm substrate from cassette storage to a transfer station. At the
transfer station, the substrate is centered in the loadcup. The
carrier head moves into place above the loadcup. Once the carrier
head and loadcup are generally aligned with one another, the
carrier head is lowered into position to collect the substrate.
Specifically, the carrier head is lowered so that the bottom of the
retaining ring's outer diameter surface 120, 175 fits into the
loadcup. To aid in centering the retaining ring 100, the narrowest
portion of the retaining ring 100 enters the loadcup first. As the
carrier head is lowered, the tapered edge 130, 190 engages the
inner surface of the loadcup, and guides the retaining ring 100
into concentric alignment with the loadcup. This alignment in turn
concentrically aligns the substrate and retaining ring 100 with one
another (assuming the substrate has been properly centered in the
loadcup).
As the carrier head is lowered further, the retaining ring's flange
195 engages and then rests upon a substantially horizontal portion
of the loadcup. This flat annular surface and maintains a parallel
disposition between the substrate in the loadcup and the retaining
ring 100 and carrier head.
Once the substrate has been loaded into the carrier head, the
carrier head lifts away to disengage from the loadcup. The carrier
head can move from the transfer station to each of the polishing
stations on the CMP apparatus. During CMP polishing, the carrier
head applies pressure to the substrate and holds the substrate
against the polishing pad. During the polishing sequence, the
substrate is located within the receiving recess 140, which
prevents the substrate from escaping. The channels 210 in the
retaining ring 100 facilitate the transport of slurry to and from
the substrate when the retaining ring 100 is in contact with the
polishing pad. Once polishing is completed, the carrier head
returns to a position over the loadcup and lowers so that the
retaining ring 100 is brought into and re-engages the loadcup. The
substrate is released from the carrier head, and subsequently moved
to the next step of the polishing sequence.
The present invention has been described in terms of a number of
embodiments. The invention, however, is not limited to the
embodiments depicted and described. Rather, the scope of the
invention is defined by the appended claims. For example, above the
horizontal section 185, the outer diameter 180 of the retaining
ring 100 can have a straight or sloped geometry. The inner diameter
155 can have a straight, sloped, or mixed straight and sloped
geometry. The retaining ring 100 can be constructed from a single
piece of plastic, using, for example, PPS, instead of being formed
from separate upper 145 and lower portions 105.
* * * * *